Sildenafil Medications
Sildenafil is a PDE5 inhibitor that promotes vasodilation to improve blood flow. It is prescribed for erectile dysfunction and certain types of pulmonary hypertension.
Buy Sildenafil Medications
Sildenafil Information
Sildenafil is a phosphodiesterase-5 (PDE5) inhibitor that improves blood flow by enhancing cyclic guanosine monophosphate (cGMP) signaling. Initially approved by the U.S. Food and Drug Administration in 1998 for erectile dysfunction (ED) under the brand Viagra, it later earned approval for pulmonary arterial hypertension (PAH) as Revatio. In Singapore, the Health Sciences Authority (HSA) has endorsed these indications, allowing both branded and generic formulations to be dispensed. By blocking PDE5, sildenafil promotes smooth-muscle relaxation in the corpus cavernosum and pulmonary vasculature, leading to erection facilitation and reduced pulmonary pressure. Off-label, clinicians sometimes employ it for conditions such as Raynaud’s phenomenon or certain types of heart failure, though such use remains unregistered. The drug is widely available in tablet form, with generic versions offering cost-effective alternatives that can be purchased through reputable online channels. Understanding its pharmacology, therapeutic scope, and safety considerations empowers patients to make informed choices when seeking to buy sildenafil online.
What is Sildenafil?
Sildenafil belongs to the class of selective phosphodiesterase-5 inhibitors, agents that target the enzyme responsible for degrading cGMP in vascular smooth muscle. The HSA granted its first approval in 1999 for erectile dysfunction, followed by a 2005 extension for pulmonary arterial hypertension. Its molecular action centers on inhibiting PDE5, which raises intracellular cGMP levels; the resulting cascade relaxes smooth muscle and increases blood flow to targeted tissues. Commercially, sildenafil appears as the well-known brand Viagra for ED and Revatio for PAH, alongside numerous generic products that keep prices competitive. Patients in Singapore can obtain these medications through our online pharmacy, which stocks both branded and generic options to suit a range of budgets.
How Sildenafil Works
Mechanism of Action
Sildenafil binds competitively to the catalytic site of PDE5, preventing the enzyme from hydrolyzing cGMP. Elevated cGMP activates protein kinase G, which phosphorylates downstream targets, leading to reduced intracellular calcium and smooth-muscle relaxation. This effect is most pronounced in tissues where PDE5 expression is high, such as the corpus cavernosum and pulmonary arteries.
Therapeutic Effects
By preserving cGMP, sildenafil enhances nitric-oxide-mediated vasodilation. In the penis, this translates to increased arterial inflow and decreased venous outflow, facilitating erection sufficient for sexual activity. In the pulmonary circulation, the same vasodilatory response lowers pulmonary arterial pressure, improving exercise capacity and delaying disease progression in PAH patients.
Onset and Duration
Clinical trials report that oral sildenafil begins to work within 30-60 minutes for erectile dysfunction, with peak plasma concentrations reached at about one hour. The therapeutic window extends roughly four to six hours, allowing flexibility in timing sexual activity. For pulmonary hypertension, steady-state effects develop after several days of twice-daily dosing, providing continuous hemodynamic benefit.
Approved Uses and Applications
Approved Indications
- Erectile Dysfunction: HSA-approved for adult men with ED, based on robust data from randomized, double-blind studies.
- Pulmonary Arterial Hypertension: Indicated for WHO Group 1 PAH, improving six-minute walk distance and delaying clinical worsening.
Off-Label Uses
Sildenafil is occasionally prescribed off-label for conditions such as severe Raynaud’s phenomenon, high-altitude sickness, and certain types of heart failure with preserved ejection fraction. These applications are supported by smaller clinical series but lack formal regulatory endorsement, so they should be considered experimental.
Clinical Efficacy
A pivotal New England Journal of Medicine trial demonstrated that 69 % of men receiving 50 mg sildenafil achieved successful intercourse, compared with 30 % on placebo. In PAH, the Lancet published results showing a mean increase of 35 meters in six-minute walk distance after 12 weeks of 20 mg thrice daily, reflecting meaningful functional improvement.
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Brand Names and Generic Options
- Viagra® - the original 25 mg, 50 mg, and 100 mg tablets.
- Revatio® - 20 mg tablets formulated for PAH.
- Generic Sildenafil - chemically identical tablets available in 25 mg, 50 mg, and 100 mg strengths, typically at 40-60 % lower cost than brand-name versions.
Quality & Safety
We work with licensed international pharmacies that adhere to WHO Good Manufacturing Practice standards, ensuring each batch meets stringent purity and potency criteria.
Pricing & Access
Generic sildenafil tablets start at SGD 8 per 25 mg tablet, representing a substantial saving over branded pricing. All repeat orders qualify for a lifetime 10 % discount, helping maintain affordability for long-term therapy.
Discreet Delivery
Orders dispatched via express shipping arrive within ≈ 7 days, while standard delivery takes up to three weeks. Packages are sealed in unmarked, matte-finished boxes to protect privacy.
Dosing, Formulations & Administration
Available Formulations
Sildenafil is supplied primarily as oral tablets in 25 mg, 50 mg, and 100 mg strengths for ED, and 20 mg tablets for PAH. No liquid or injectable forms are approved for these indications.
Typical Dosing Ranges
- Erectile Dysfunction: Initial therapy often starts at 50 mg taken about one hour before sexual activity. Depending on efficacy and tolerability, clinicians may adjust the dose to 25 mg or 100 mg.
- Pulmonary Arterial Hypertension: Recommended dose is 20 mg three times daily, taken at evenly spaced intervals to maintain steady plasma levels.
These examples reflect common clinical practice; the exact regimen must be individualized by a qualified healthcare professional.
Administration Guidelines
Sildenafil can be taken with or without food, but a high-fat meal may delay absorption and postpone onset by up to two hours. For PAH, tablets should be swallowed whole with water; crushing or chewing is not advised. Consistency in timing-especially for the thrice-daily PAH schedule-optimizes therapeutic effect.
Note: Only a licensed clinician can determine the appropriate dose based on your medical history, concurrent medications, and specific health goals.
Safety Profile & Considerations
Common Side Effects
- Headache - reported in ~16 % of users.
- Facial flushing - appears in ~10 % of patients.
- Dyspepsia - occurs in 7-9 % of cases.
- Nasal congestion - seen in ~8 % of participants.
- Visual disturbances (e.g., blue-tinted vision) - affect less than 3 % of users.
These events are usually mild and resolve without intervention.
Serious Adverse Events
Rare but critical complications include sudden hearing loss, non-arteritic anterior ischemic optic neuropathy, priapism lasting longer than four hours, and severe hypotension when combined with nitrates. Immediate medical attention is warranted for any of these symptoms.
Contraindications
- Concurrent use of nitrate therapy (e.g., nitroglycerin) due to risk of profound hypotension.
- Uncontrolled hypertension or recent myocardial infarction.
- Known hypersensitivity to sildenafil or any component of the formulation.
Drug Interactions
- CYP3A4 inhibitors (ketoconazole, erythromycin) can increase sildenafil plasma concentrations, necessitating dose reduction.
- CYP3A4 inducers (rifampin, carbamazepine) may lower effectiveness.
- Other PDE5 inhibitors or guanylate cyclase stimulators (riociguat) should not be co-administered.
- Alpha-blockers may augment the blood-pressure-lowering effect.
Special Populations
- Pregnancy & Breastfeeding: Use is not recommended; safety data are lacking.
- Elderly: Reduced renal clearance may increase exposure; start at the lower end of the dosing range.
- Hepatic or Renal Impairment: Moderate impairment warrants a dose reduction; severe dysfunction may contraindicate use.
- Pediatric Use: Not approved for ED; PAH treatment is limited to specific age-restricted trials and must be prescribed by a specialist.
Frequently Asked Questions
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How does sildenafil differ from tadalafil? Sildenafil’s plasma half-life is about 4 hours, while tadalafil lasts up to 36 hours, allowing once-daily dosing. Both inhibit PDE5, but tadalafil’s longer duration makes it suitable for more spontaneous use.
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How long does sildenafil take to work for erectile dysfunction? Most men notice an erection-facilitating effect within 30-60 minutes after ingestion, with peak efficacy around one hour.
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What is the typical onset of action for sildenafil in pulmonary hypertension? Clinical improvement in exercise capacity generally appears after 2-3 weeks of twice-daily dosing, though steady-state plasma levels are reached after 4-5 days.
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Can I take sildenafil with alcohol? Moderate alcohol consumption does not markedly affect sildenafil’s efficacy, but excessive drinking may exacerbate hypotension and dizziness.
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What foods should I avoid while taking sildenafil? High-fat meals can delay absorption, postponing the onset of action. It is advisable to take the tablet with a light snack or on an empty stomach for faster effect.
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What should I do if I experience a headache after taking sildenafil? Over-the-counter analgesics such as acetaminophen are generally safe, but if headaches are severe or persistent, consult a healthcare provider.
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Is it safe to combine sildenafil with antihypertensive medication? Most antihypertensives are compatible, yet concurrent use with nitrates is prohibited. Discuss your blood-pressure regimen with a clinician before starting sildenafil.
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Can sildenafil cause vision problems? Transient color vision changes occur in a small minority; permanent visual loss is extremely rare but requires urgent evaluation.
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What are the risks of taking sildenafil daily? Daily dosing is approved for PAH and may be used off-label for ED in select patients. Long-term safety data indicate a stable side-effect profile, though ongoing monitoring is recommended.
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What information should I provide my doctor when discussing sildenafil?
- Complete list of current medications, including over-the-counter drugs and supplements.
- History of cardiovascular disease, especially any nitrate use.
- Current blood-pressure readings and any recent cardiac events.
- Specific treatment goals (e.g., frequency of sexual activity or improvement in exercise tolerance).
Disclaimer
The information provided about sildenafil is for general knowledge only. It does not replace professional medical consultation or the official prescribing information for medications containing this ingredient. All treatment decisions, including dosing, formulation selection, and monitoring, should be made under the supervision of a qualified healthcare provider who can assess individual medical history, current medications, and specific health needs. We assume all readers are responsible adults capable of making informed decisions about their health. Our online pharmacy offers access to medications containing sildenafil for individuals who may have limited availability through traditional pharmacies, prescription-based insurance schemes, or who are seeking affordable generic alternatives. Always consult your doctor before starting, changing, or discontinuing any medication containing sildenafil.
